Very strange well issue occurred today...

[Mooch91]

Hi all. Would appreciate any ideas on a very strange well issue that occurred for me this morning. Sorry for the length - hoping the detail might help.

Background: 15-year old new construction with deep well in central PA. Unsure of depth. Goulds 3/4 hp submersible, 20 gal pressure tank, 40/60 in/out settings. CPVC piped home and outdoor irrigation system fed from the same well (backflow protected). Never any issues with the pump, tank, well recovery, or well running dry during the last 10 years we've been in the home, even during some significant drought situations.

Situation: This morning we woke to find a considerable amount of air in our home's piping which must have occurred overnight.

My suspicion: Our irrigation runs overnight a few times a week for about 2-3 hours. Last night our irrigation started, and about 1/2 hour in, the system lost flow and pressure. With valves to the in-ground lines open, and no pressure from the well, the plumbing system drained down from the house and in to the yard. About an hour later, the flow/pressure returned and the irrigation resumed operating, and the lines in the house re-filled, trapping air.

Evidence: I continuously monitor current draw by the pump. My irrigation is designed to run the well system without pump cycling - it's designed for full pump flow, and the pump stays on until the system shuts down. At about 1/2 hour in, I see pump power consumption briefly increase from a typical 1700W up to 2500W, and then it drops down to about 20W for the next hour before returning. The pump normally shows 0W when it's fully idle, so it appears to have been trying to run during that time.

When I woke and realized something was wrong, I immediately changed all filters (house only, none on the irrigation lines), drained the pressure tank, and checked the pressure on the bladder with the tank empty and open (was at 32 psi and I increased it to 38, which is 2 psi below the cut-in pressure). Once the air cleared from the house, all has been good.

What I can't figure out is WHY this happened. My guess is that the well level might have dropped below the pump for that one hour period. Or pump lost prime or bound up. Or plugged up at the inlet. And then suddenly recovered. I would think if there were a blockage on the discharge side of the pump, I'd see high power consumption and not low like I did.

Any guesses as to why this happened?

And any concerns for the piping in the house? If the plumbing siphoned out in to the irrigation system, I would think it would have had to have created a vacuum in the piping, and I don't know what kind of damage that can cause to CPVC (which is already an issue), hoses, valves, and fittings.

Thanks!

 

[Valveman]

Sorry for your problem. Even though you are doing everything right on the irrigation by setting zones large enough to keep the pump running continuously, cycling still maybe the cause of the problem. In 15 years just cycling for house use alone will probably be enough to cause problems. If there had been a blockage or the well ran dry, the power consumption would drop, not increase. But it would not drop as low as 20W, but about half of normal running power or 700w give or take. 20W maybe the power used by the pump controller itself, but the motor isn't running. When the power used went from 1700W to 2500W, the overload in the motor will trip. It usually only takes a minute or two before the overload cools down, automatically resets, and starts the motor. It may have tried several times and just tripped off again, and happened too fast for your monitor to see it, because it shouldn't have taken hours to come back on.

After it shuts off and the sprinklers drain the system, you just have to bleed the air out of everything.

1700 watts or 9.8 amps is max load for a 1HP motor. Max watts will cause max heat to the motor windings. Heat will swell the epoxy encased motor windings and shorten its life. Motors are designed to last an average of 7 years worth of cycling. But even without excessive cycling, running at max amps/watts will shorten the motor life as well. Running the motor at reduced amperage, like when running fewer sprinklers and using a Cycle Stop Valve to keep from the pump from cycling, could cause your 1700W motor to run a say 1500W, which would run cooler and last longer. If I can't de-rate the motor load like this by using fewer sprinklers at one time, I try to oversize the motor. Running a 1HP pump with a 1.5HP motor capable of 2150W, would make it run cooler at the 1700 watts needed for the amount of sprinklers being used.

 

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[Mooch91]

Sorry for your problem. Even though you are doing everything right on the irrigation by setting zones large enough to keep the pump running continuously, cycling still maybe the cause of the problem. In 15 years just cycling for house use alone will probably be enough to cause problems. If there had been a blockage or the well ran dry, the power consumption would drop, not increase. But it would not drop as low as 20W, but about half of normal running power or 700w give or take. 20W maybe the power used by the pump controller itself, but the motor isn't running. When the power used went from 1700W to 2500W, the overload in the motor will trip. It usually only takes a minute or two before the overload cools down, automatically resets, and starts the motor. It may have tried several times and just tripped off again, and happened too fast for your monitor to see it, because it shouldn't have taken hours to come back on.

After it shuts off and the sprinklers drain the system, you just have to bleed the air out of everything.

1700 watts or 9.8 amps is max load for a 1HP motor. Max watts will cause max heat to the motor windings. Heat will swell the epoxy encased motor windings and shorten its life. Motors are designed to last an average of 7 years worth of cycling. But even without excessive cycling, running at max amps/watts will shorten the motor life as well. Running the motor at reduced amperage, like when running fewer sprinklers and using a Cycle Stop Valve to keep from the pump from cycling, could cause your 1700W motor to run a say 1500W, which would run cooler and last longer. If I can't de-rate the motor load like this by using fewer sprinklers at one time, I try to oversize the motor. Running a 1HP pump with a 1.5HP motor capable of 2150W, would make it run cooler at the 1700 watts needed for the amount of sprinklers being used.

@Valveman

Thanks so much for your reply. Thanks also for some additional insights. I had a reasonably technical understanding of well pumps and tanks, but your info was very helpful for additional info.

I had always understood that for an irrigation system, the desire was to keep the pump running continuously, so design it for the output of the pump. Admittedly, I never actually measured the flow coming directly from the pump, I just scaled my nozzles up until the system ran continuously at about 50 psi at the pump outlet. This was about 14-15 gpm total flow as indicated by the sum of the nozzle flow rates. This is at 50 psi at the sprinkler heads, though, and I'm confident I have significant losses between the pump and the heads, so realistically I'm getting 30-40 psi at the heads and probably closer to 10-11 gpm. Hadn't had a problem for about 10 summers of operating in this way.

I did look at the controller which says 8A max, so at 220V, that would be 1760W. Each time the pump runs to re-pressurize the tank it appears to get up to 1680-1700W. I can't actually get back to the data from when it tripped out to see what the steady state power reading was before the pump stopped pumping. It may in fact have been cycling on and off a number of times per minute when it looks like it wasn't pumping the other night. The 20W I was seeing might have been the power consumption averaged over 1 minute instead of an instantaneous number (I lose resolution on the instantaneous measurements after a period of time).

This system has always worked "just ok" - based on the plumbing design of the house, pressure at the furthest reaches always seemed a little low, and its output for an acre of irrigation has me needing to run for long durations and fewer zones at a time. I'm not inclined to go changing out the pump at this point, but if and when it does go bad, I'll likely have the well evaluated for a larger pump to better support the irrigation in particular.

 

[Valveman]

The larger the pump the more important a Cycle Stop Valve is to allow it to work like a small pump when needed without cycling. If it is already tripping the overload, the motor is compromised and you need to be ready to get a new one soon. If you need more pressure at the sprinklers, get a pump that will do more pressure and turn up the pressure switch.

 

[Mooch91]

The larger the pump the more important a Cycle Stop Valve is to allow it to work like a small pump when needed without cycling. If it is already tripping the overload, the motor is compromised and you need to be ready to get a new one soon. If you need more pressure at the sprinklers, get a pump that will do more pressure and turn up the pressure switch.

Thanks. I was hoping what I experienced was a fluke of some sort and that the pump is not on the way out. It's probably worth seeking out a well driller or specialist to explore my options now rather than when it has failed. I'll look more deeply in to the Cycle Stop Valve as well. Thanks.

 

[Valveman]

There really is no repair to a submersible pump/motor. Just run it until it quits to get as much good as you can out of it. The well driller or "specialist" won't know as much as you do about it, as they don't read these forums. Lol! No, but really, you need to educate yourself or you are subject to whatever the "specialist" wants to sell you, which is usually the most expensive and least dependable system you could buy. That is how they make money. Just make sure the pump is not cycling when irrigating and the tank air charge is good. You may get 10 years or 10 days out of that pump. If I did these things and it still tripped the overload a couple times, I might do something preempted and get it fixed before it quits completely.

 

[Mooch91]

There really is no repair to a submersible pump/motor. Just run it until it quits to get as much good as you can out of it. The well driller or "specialist" won't know as much as you do about it, as they don't read these forums. Lol! No, but really, you need to educate yourself or you are subject to whatever the "specialist" wants to sell you, which is usually the most expensive and least dependable system you could buy. That is how they make money. Just make sure the pump is not cycling when irrigating and the tank air charge is good. You may get 10 years or 10 days out of that pump. If I did these things and it still tripped the overload a couple times, I might do something preempted and get it fixed before it quits completely.

Thanks.

I was thinking of asking a well driller about the viability of a larger pump before it actually fails and I'm under the gun for a quick replacement. My understanding of wells is that it's not just about the size of the pump, but that the well itself needs to have the "capacity" to provide the water at a particular rate. So upsizing a pump could cause the water level in the well to drop and reduce/lose flow until the well itself recovers.

 

[Valveman]

Thanks.

I was thinking of asking a well driller about the viability of a larger pump before it actually fails and I'm under the gun for a quick replacement. My understanding of wells is that it's not just about the size of the pump, but that the well itself needs to have the "capacity" to provide the water at a particular rate. So upsizing a pump could cause the water level in the well to drop and reduce/lose flow until the well itself recovers.

That is correct. You really don't want a 10 GPM pump if the well can only provide 5 GPM. However, even though a well only makes say 5 GPM, the water stored in the well from the pump to the static level will allow the pump to produce more than 10 GPM for a certain period of time. This is usually enough time to handle peak demands in the house. In these cases it is best to have a 10 GPM pump in a 5 GPM well, as the house may occasionally use more than 5 GPM for short times.

I would guess your 3/4HP pump is a 10 GPM series. But with a 20 gallon tank that only holds 5 gallons of water it could very well be only a 5 GPM pump. Running wide open a 10 GPM pump will put out about 17 GPM where a 5 GPM pump will max out at 8-9 GPM at the most. A bucket test with the pump running wide open at low pressure would tell you which pump you have.

 

[Mooch91]

That is correct. You really don't want a 10 GPM pump if the well can only provide 5 GPM. However, even though a well only makes say 5 GPM, the water stored in the well from the pump to the static level will allow the pump to produce more than 10 GPM for a certain period of time. This is usually enough time to handle peak demands in the house. In these cases it is best to have a 10 GPM pump in a 5 GPM well, as the house may occasionally use more than 5 GPM for short times.

I would guess your 3/4HP pump is a 10 GPM series. But with a 20 gallon tank that only holds 5 gallons of water it could very well be only a 5 GPM pump. Running wide open a 10 GPM pump will put out about 17 GPM where a 5 GPM pump will max out at 8-9 GPM at the most. A bucket test with the pump running wide open at low pressure would tell you which pump you have.

I believe at one point I confirmed it to be about 10 gpm. Here are the specs.

EDIT: Looking up the model number confirms 10 gpm.

 

[Reach4]

Evidence: I continuously monitor current draw by the pump. My irrigation is designed to run the well system without pump cycling - it's designed for full pump flow, and the pump stays on until the system shuts down. At about 1/2 hour in, I see pump power consumption briefly increase from a typical 1700W up to 2500W, and then it drops down to about 20W for the next hour before returning. The pump normally shows 0W when it's fully idle, so it appears to have been trying to run during that time.

When I woke and realized something was wrong, I immediately changed all filters (house only, none on the irrigation lines), drained the pressure tank, and checked the pressure on the bladder with the tank empty and open (was at 32 psi and I increased it to 38, which is 2 psi below the cut-in pressure). Once the air cleared from the house, all has been good.

What I can't figure out is WHY this happened. My guess is that the well level might have dropped below the pump for that one hour period. Or pump lost prime or bound up. Or plugged up at the inlet. And then suddenly recovered. I would think if there were a blockage on the discharge side of the pump, I'd see high power consumption and not low like I did.

I cannot think of a good scenario with that current increasing time profile. Temporary partially mechanically bound up kinda does, but I have a hard time picturing how that would happen. The 20 watts could not happen if the pump is running, but maybe that is the draw from the pump protector after it has shut down the pump. So maybe the motor swells up, adds friction, which raises current, and then a protector that consumes 20 watts shuts the pump down for a while.

 

[Mooch91]

I cannot think of a good scenario with that current increasing time profile. Temporary partially mechanically bound up kinda does, but I have a hard time picturing how that would happen. The 20 watts could not happen if the pump is running, but maybe that is the draw from the pump protector after it has shut down the pump. So maybe the motor swells up, adds friction, which raises current, and then a protector that consumes 20 watts shuts the pump down for a while.

Thank you for weighing in. The data I have is limited in that the second-by-second data starts to get averaged after a period of time, so there are artifacts in what I can see. So what I'm observing as 20W could actually be the pump cycling 10x in a minute consuming 1500W each time, but averaging to 20W across that minute. I do have some evidence that it was in fact cycling near 5-6X a minute - I have a current sensing switch on one leg of the pump wiring which was turning on and off frequently during that time - but I can't confirm if that was true cycling, or the current load just being close to the setpoint of the switch. In any case, there should be no pump cycling when the irrigation is running - each zone runs continuously when on.

Power/current definitely increased then dropped off to near nothing for an hour and started pumping again. On my basement cameras I can actually hear the plumbing in the house fill back up when it starts pumping again after that hour.

Knock on wood, no problems since that event. But I also haven't tried to run the irrigation since, so it's been working fine for general showering, clothes washing, and sink use.